Switch



L. MAUERER Sept. 23, 1958 SWITCH Filed Oct. 3, 1956 INVENTOR [EDPULDMfil/E'AER UnitediStates atent Qffice SWITCH Leopold; Mauerer,Milwaukee, Wis., assignor to Hevi- Duty Electric Company,-Milwaukee,Wis., a corporation of Wisconsin.

Application October 3, 1956, Serial No. 613,731

4 Claims. (Cl. 200-113) The present invention relates to electriccurrent overload disconnectors or switches, and particularly to a newand improved thermal overload disconnector of simplified design and toan inexpensive method of making the same.

Prior-known disconnectors of the type referred to usually-comprise aplurality of components requiring stampings, rivets, and jigs in theirfabrication. Fixtures are often required to maintain the components inproper relation to each other during assembly, including the solderingoperation to join the parts that are adapted to separate in order tobreak the circuit in the event of overload.

The principal object of this invention is to provide a simple thermaloverload disconnect that can be fabricated with ease.

Another objectof the invention is to eliminate the need for stamped-outcomponents for riveting to the disconnect base and for separatefastening meansto hold the currentcarrying conductor on said base.

One aspect of the present invention contemplates the use of a resilientelectrical conductor having diverging leg portions, each having aterminal portion for connection into a transformer circuit or the like.The terminal portions can have suitable wires soldered or fastenedthereto for connecting the disconnector in the circuit. An intermediateportion of the conductor between the diver ing leg portions includes apair of parallel axially-contacting portions formed by bending theconductor back on itself through 180. The parallel axially-contactingportions are soldered together with a solder having a predeterminedmelting point, and the elbow joining the axiallycontacting portions isthen severed from the conductor. In assembling the conductor to the basemember, which may be of thin insulating material, the diverginglegsareforced toward each other, so that a torsional stress is set up in theconductor tending to separate the soldered parallel.;axially,.contactingportions, Preferably, a clip portion is arranged to cooperate withholding means on said base. The holding means may comprise notches onopenings in the base spaced so as to hold the legs in a manner tendingto separate the axially-contacting portions. In one aspect, the notchescan have tapered margins so that when the formed conductor is forcedtherein as it is mounted on the base, a prestressing of the parts willtake place, also tending to cause the parallel axiallycontactingportions to separate. In operation, any dangerous overload currentpassing through the circuit including the disconnect will cause heatingof the transformer or the like which will result in melting of thesolder and consequent separation of the soldered portions, therebybreaking the circuit. In such a structure when used in conjunction witha transformer or the like, the heat causing the melting of the soldermay be supplied mainly by the transformer coil, or it may be supplied inwhole or part by the overload current itself. In one form, the devicecan be fastened with ease by tape, string or similar means to theperiphery of a coil or other parts of an electrical device in which heatis generated.

The above, other objects and novel features of the in- Fig. 3 is a viewof another portion of the conductor of Fig. l as viewed by looking inthe direction of the arrows along line 33 of Fig. 1; v i

Fig. 4 is a front elevational view of an overload disconnect to whichthe principles of the invention-have been applied; i i

Fig. 5 is an end elevational-viewof the disconnect of Fig. 4 as viewedby looking in the direction ofthear rows along line 55 of Fig. 4; and

Fig. 6 is a perspective view of thedisconneetof Figs. 4 and 5.

Referring to the drawing, and in particular to Fig. ;1, acurrent-carrying conductor 10, preferably having a substantial degree ofinherent resilience-in the order of that possessed by an alloy wire, e.g.,-a #20 gagePhosphor bronze, includes a terminal portion 11- formed'bybending a short length of said conductor-back on itself to form twoshort parallel closely-spaced or contacting leg portions which arejoined by a semicircular elbow 13.

The conductor 10 extends at right angles to, butvin -thesame plane asthe leg 11, for a substantial distance forming another leg 14. From theend of-leg- 14, oppositeleg 11, conductor 10 extends for a shortdistance at rightangles to and within the same plane as that includinglegs 11 and 14, forming a portion 15- (Fig. 3) for a purpose to bedescribed later. At the end of the portion 15 opposite its connection toleg 14, conductor 10 extends at right angles, and within a plane atright angles to the plane including legs 11 and14, forming a leg 16; 1The conductor 10 is then bent back on itself, forming a leg 17 in thesame plane as, and in axialcontact with the leg 16, and joined to thelatter by a semicircular elbow portion 18. At the end of the leg 17,opposite elbow 18, conductor 10 extends substantially in the form of aU-shaped clip 19 lying within the same plane including legs 16 and 17.At the end of the U-shaped clip-19, opposite its connection to leg 17,conductor 10 extends for a short distance, forming a portion 20 within aplane at right angles to the plane including .U-shaped clip 19 for apurpose to be described later. Finally, the ,conductor 10 extends atright angles to the portion'20, forming a leg 21 that lies within aplane diverging from the plane including leg 14, and at an acute angleto the plane including the portion 20 and one leg of the U-shaped clip19'. At the free end of the leg 21 a terminal portion 22 is providedthat is identical with terminal portion 11.

The contacting legs 16 and 17 are joined by solder While being held inclose proximity by elbow 18, the solder being chosen to melt 'at apredetermined temperature. In use in conjunction with transformers orsimilar electrical devices it is desirable that the heat of thetransformer cause operation. Thus, the melting point of the soldershould be such that the switch will open before damage is done, forexample, before the winding conductors burn open. After the solderingoperation, the elbow 18 is severed from the conductor 10 as shown inFigs. 4 and 6.

Referring to Figs. 4 and 6, the disconnect of this inventioncontemplates the use of an insulating base that may be made of anyinsulating material of any suitable thickness. In the embodimentdisclosed, it is shown as comprising a thin, fibrous sheet 23 havingnotches 24 Patented- Sept. 23, 1958- and 25 with tapering margins in itsone edge, spaced apart a distance equal to the distance between theportions and of the conductor 10. Holes 26 and 27 are formed within thesheet 23 a distance apart equal to the distance between the notches 24and 25, and preferably located in alignment therewith.

The length of the portions 15 and 20 of the conductor 10 is slightlygreater than the thickness of the base 23 so that upon assembling theconductor 10 and the base 23, the legs 14 and 21 lie on the one side ofthe base 23, while the legs 16, 17 and U-shaped clip 19 lie on theopposite side of base 23. With the terminal 11 extending through theopening 26, the terminal 22 does not align itself with opening 27 inbase 23. This is due to the angularly-disposed plane including leg 21.However, forcing leg 21 to a position where terminal 22 thereofregisters with, and extends through opening 27 places a torsional stressin the leg of U-shaped clip 1.9 con nected to leg 21. Accordingly, thistorsional stress is transmitted to leg 17, tending to separate it fromcontact with leg 16 against the holding force of the soldered jointbetween legs 16 and 17. The loop between notches 24 and also istensioned or prestressed in such a manner as to tend to cause opening asa result of sliding the same down or along the tapered walls of notches2' 1 and 25.

With the terminals 11 and 22 connected into a circuit including thelow-voltage secondary coil of a transformer or the like, upon anysecondary short circuit, the transformer will heat up until the solderof the connection between legs 16 and 17 melts, whereupon the leg 17will separate form leg 16 due to the torsional stress in U- shaped clip19 and the prestressing of the loop, thereby opening the secondarycircuit of the transformer.

Although the various features of the new and improved disconnector havebeen shown and described in detail to fully disclose one embodiment ofthe invention, it will be evident that numerous changes may be made insuch details, and certain features may be used without others withoutdeparting from the principles of the invention except as defined inappended claims.

What is claimed is:

1. In an overload disconnect having a base including spaced notches andperforations aligned therewith, an electrical conductor having inherentresilience; said conductor having two leg portions in parallelcontacting relation and joined together by solder having a predeterminedmelting point; normally diverging legs connected to said legs that aresoldered together, the angle between said diverging legs differing fromthat defined between said notches and aligned perforations, saidnormally diverging legs being mounted in said notches and perforationsand urged thereby toward parallelism with respect to each other so as toset up a torsional stress in one of the soldered legs, tending toseparate it from the other soldered leg.

2. In a thermal overload disconnect, a base; a conductor lying along oneface of said base; another conductor parallel with said conductor andjoined thereto by solder having a predetermined melting point; legportions attached to and normally diverging away from said parallelsoldered conductors; a terminal at the free end of each of said legportions; and means on said base for maintaining said diverging legportions in relation to each other different from their normal relationso as to tend to separate said leg portions.

3. In a thermal overload disconnect, an insulating base; a conductorlying along one face of said base; another conductor parallel with saidconductor and joined thereto by solder having a predetermined meltingpoint; a leg portion extending at substantially right angles from saidone parallel conductor; another leg portion normally extending at anobtuse angle from said other parallel conductor; an intermediate portionbetween said other leg portion and its corresponding parallel conductor;and means on said base for maintaining said diverging leg portions inrelation to each other different from said obtuse angle so as to set upa torsional stress tending to separate the conductors joined withsolder.

4. An overload disconnect comprising an insulating base adapted to beplaced adjacent to a device to be controlled, said base havingperforations therein; an electrical conductor having a pair of legsjoined by soldering and legs extending from each of said pair of legs,said last mentioned legs being mounted in said perforations and on saidbase so as to hold said last mentioned legs at a different anglerelative to each other than when in their normal free condition, therebysetting up a stress tending to separate said pair of legs joined bysolder and break the circuit, said conductor being mounted on said basewith terminal portions extending through said perforations to whichother conductors can be joined for connecting said overload disconnectinto a circuit to be controlled.

References Cited in the file of this patent UNITED STATES PATENTS819,608 Sherwood May 1, 1906 1,309,233 Akin July 8, 1919 1,684,108Phelps Sept. 11, 1928 1,735,133 Schmidt Nov. 12, 1929 2,056,760 AustinOct. 6, 1936 2,391,680 Cook Dec. 25, 1945 2,493,434 Yonkers Jan. 3, 19502,530,228 Cihlar et al. Nov. 14, 1950 2,727,110 Van Hoorn Dec. 13, 19552,738,396 Strafiford Mar. 13, 1956 2,740,187 Jacobs et al. Apr. 3, 1956

